IMPORTANT - Read this first!

Note: To simplify these diagrams, we have not shown the earth cables - but all circuits MUST have the earth cable correctly installed.

We've shown wires in red to indicate that they are new wires, but it doesn't really matter what colour you use.

To protect the module a suitable rated overcurrent protection fuse must be installed on the Live input.

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One of the things that confuses people the most is installing home automation into an existing 2-Way lighting system. This application note looks at how a Fibaro Dimmer 2 module can be installed to control a 2-Way lighting system with Neutral available.

Firstly, what do we mean by 2-Way lighting?

This simply refers to a lighting system where one light is controlled by two light switches. Examples of this are where a room has two entrances (each needs a light switch) or for a hall light that can be controlled from the hall and the upstairs landing.

This guide provides alternative ways to use a Fibaro Dimmer 2 module in a 2-way lighting system. This is a different style of creating a 2-way lighting circuit used in some countries but uncommon in most UK buildings. It uses a 2-core (+ earth) cable between the two switches, instead of the more typical 3-core (+ earth) cable.

For information on how to physically install a Z-Wave module take a look at our guide here.

To know more about how Z-Wave modules work with different switch types make sure to read our guide here.

Alternate 2-Way Lighting Circuit (with Neutral)

Figure 1: Alternate 2-Way Lighting Circuit (with Neutral)

This system uses a 2-core (+ earth) cable between the two switches, instead of the more typical 3-core (+ earth) cable. The main challenge with this system is that neither Switch locations have access to both Permanent Live and Switched Live.

This type of lighting system uses "Toggle" (latching) switches. These latch in position - for instance when you press the switch to On, the switch physically stays in the On position. These are the standard light switches you'll find already fitted in your home.

The module can also be used with a variety of "Momentary" switch types and configurations. Momentary switches, also known as Retractive or Bell-Push, only remain in the On state while you press them, they return to the Off state when the button is released.

This doesn't mean that you have to keep holding the button to keep the light on. The module's internal controls automatically keep the light on when the button is released.

More information about how the Fibaro Dimmer 2 works with different switch types is available here.

We can install the module into the 2-Way circuit in various different ways shown below. We've separated out the diagrams based on whether you need to install the module at Switch A or Switch B position.

Fibaro Dimmer 2 Connections

The Fibaro Dimmer 2 has six terminals to connect it to the electrical wiring:

L – Live

S2 – connection to Switch 2

S1 – connection to Switch 1

Sx – switch common

N – Neutral (this is connected to Sx in 2-wire installations)

~ (Output) – connected to light or load

Fibaro Dimmer 2 Parameter Setting:

The following parameters may need to be set:

20 - 0 - enables the module to work with momentary switch (default)

20 - 1 - enables the module to work with a toggle switch

20 - 2 - enables the module to work with a 3-position momentary switch

26 - 1 - enables the modules' S2 switch to also control the load (default 0)

Installation at Switch A position

You will install the Fibaro Dimmer 2 module at the Switch A position where it has access to Permanent Live.

In this case we keep the standard Toggle switches connecting Switch A "L1" to the module's S1 input and Switch B "L1" to the module's S2 input with the "COM" wire connected to the module's Sx output. Live is wired to L terminal and an additional 2-core cable is added to take Switched Live to the Load and Neutral back to the module.

The Dimmer 2 is then configured to accept S2 as the second switch control of the Dimmer module.

This gives simple On / Off control of the light from the switches but you will still be able to control the dimming level over Z-Wave if required.

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

20 - 1 - enables the dimmer to work with a toggle switch (default is 0 for a momentary switch)

26 - 1 - enables the dimmers S2 switch to also control the dimmer (default 0)

By using Momentary switches the 2-Way wiring can be simplified - connect both Switch A and Switch B "L1" to the module's S1 input and the "COM" wire to the module's Sx output. Live is wired to L terminal and an additional 2-core wire is added to take Switched Live to the Load and Neutral back to the module.

In this case we keep the standard Toggle switches connecting Switch A "L1" to the module's S1 input and Switch B "L1" to the module's S2 input with the "COM" wire connected to the module's Sx output. Live is wired to L terminal and re-wire Switched Live (Dimmer Output) and Neutral to Switch A position.

The module is then configured to accept S2 as the second switch control of the Dimmer module.

This gives simple On / Off control of the light from the switches but you will still be able to control the dimming level over Z-Wave if required.

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

20 - 1 - enables the dimmer to work with a toggle switch (default is 0 for a momentary switch)

26 - 1 - enables the dimmers S2 switch to also control the dimmer (default 0)

By using Momentary switches the 2-Way wiring can be simplified - connect both Switch A and Switch B "L1" to the module's S1 input and the "COM" wire to the module's Sx output. Live is wired to L terminal and re-wire Switched Live (Dimmer Output) and Neutral to Switch A position.

Fibaro Dimmer 2 Parameter Setting:

Sometimes you may require a 2-Way or multi-way lighting circuit where physical wiring doesn't already exist, or perhaps you need to re-purpose the existing wiring for something else.

Z-Wave makes this possible using something known as "Associations" - where one Z-Wave device can control another Z-Wave device directly without inter-connecting wiring. More information on Associations can be seen in our guides here and here.

To create this circuit you simply install the module to suit either Toggle or Momentary switches and use the original "L1" wire to take Switched Live and original "L2" wire to take Neutral to Switch B position. A battery powered Z-Wave wall switch such as the Nodon Wall Switch can then be Associated to the module.

Don't forget to configure the module for Toggle or Momentary switches!

Installation at Switch B position

You will install the Fibaro Dimmer 2 module at the Switch B position where it has access to Switched Live and Neutral.

In this case we keep the standard Toggle switches connecting Switch A "L1" to the module's S1 input and Switch B "L1" to the module's S2 input with the "COM" wire connected to the module's Sx output. An additional wire is added to take Live to Switch B position.

The Dimmer 2 is then configured to accept S2 as the second switch control of the Dimmer module.

This gives simple On / Off control of the light from the switches but you will still be able to control the dimming level over Z-Wave if required.

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

20 - 1 - enables the dimmer to work with a toggle switch (default is 0 for a momentary switch)

26 - 1 - enables the dimmers S2 switch to also control the dimmer (default 0)

By using Momentary switches the 2-Way wiring can be simplified - connect both Switch A and Switch B "L1" to the module's S1 input and the "COM" wire to the module's Sx output. An additional wire is added to take Live to Switch B position.

In this case we keep the standard Toggle switches connecting Switch A "L1" to the module's S1 input and Switch B "L1" to the module's S2 input with the "COM" wire connected to the module's Sx output. Re-wire Live to Switch B position.

The Dimmer 2 is then configured to accept S2 as the second switch control of the Dimmer module.

This gives simple On / Off control of the light from the switches but you will still be able to control the dimming level over Z-Wave if required.

Fibaro Dimmer 2 Parameter Setting:

The following parameters need to be set:

20 - 1 - enables the dimmer to work with a toggle switch (default is 0 for a momentary switch)

26 - 1 - enables the dimmers S2 switch to also control the dimmer (default 0)

By using Momentary switches the 2-Way wiring can be simplified - connect both Switch A and Switch B "L1" to the module's S1 input and the "COM" wire to the module's Sx output. Re-wire Live to Switch B position.

Here we replace Switch A with a Z-Wave Wall Switch. Connect Switch B “L1” to the module's S1 input with the "COM" wire connected to the module's Sx output. We use the original "L1" wire to bring over Live from Switch A position to Switch B position.

Any unused wires from the original 2-core between the two switches should be safely terminated.

A battery powered Z-Wave wall switch such as the Nodon Wall Switch can then be Associated to the module. More information on Associations can be seen in our guides here and here.

Here we connect Switch A “L1” to Module A S2 input. Connect Switch C “L1” to the Module B S1 input with the "COM" wire connected to the Module B Sx output. We use the original "L1" wire to bring over Live from the first switch position.

Any unused wires from the original 3-core between the two switches should be safely terminated.

More information on how to use a Secondary Switch with a Fibaro Dimmer 2 module can be found here.

Note: power to module at Switch A not shown as this would typically be taken care of for switching the other gang in a 2-gang switch.